It is known in the art to which this invention pertains to electrodeposit upon a basis metal a metallic material exemplified by zinc, copper, nickel or the like utilizing in the electroplating bath polyamines as one of the additives thereto. Polyamines having the property of enhancing the brightness and also contribute to grain refinements of the deposit. However, polyamines are relatively potent or active and can cause embittlement of the cathode deposit, and contribute to a relatively poor bond between the metal substrate and the electroplate.
The literature is also replete with references to the utilization in a zinc plating bath containing polyvinyl alcohol, an aromatic aldehyde and a chelating agent, however, experience has indicated that under normal bath conditions the polyvinyl alcohol tends to accumulate and rise to a relatively high concentration in the bath, and among other contributing difficulties, it has been found that certain aromatic aldehydes may at times be in relatively short supply.
The prior art which has endeavored to deal with the problems above set forth are U.S. Pat. Nos. 2,451,426; 3,317,412; 3,594,291; and 3,694,330, as well as German Patent No. 1,521,029. However, applicants have found that when these teachings of the prior art are followed there is not obtained a product having the requisite degree of brightness, particularly in the low current density areas, nor can the desired degree of ductility be at all times expected.